a lot of hot button issues. >> yeah. the most recently retired justices were johnpaulstevenswentout at 90. david souter 69, sandra day o'connor 75. is there a tradition of when justices usually retire, be it age, or time served? >> well, they're like most human beings. a lot of factors weigh in. there is -- there was a tradition where justices would tend to retire during the term of a president that was at the same party that appointed them. but we know neither justices souter nor stevens did that. they were both republican employees and went out during president obama's term. life circumstances can drive retirement decisions. so it's really not scientifically predictable or politically predictable. >> do you see any most likely candidates if another seat opens up under president obama? >> you know, i think if president obama, first of all, justice ruth bader ginsburg i think the pressure to replace her with another woman appointee would be enormous. we've made progress in getting a third of the court female and i don't think president obama or any president would want to go backwar